Which of the following poker hands is the best? Assume one standard 52-card deck is used. The game is five-card draw, so there are no community cards, with no wild cards.
For reference, here are the rankings of poker hands.
Royal flush - A, K, Q, J, 10, all the same suit.
Straight flush - Five cards in a sequence, all the same suit.
Four of a kind - Four cards all of the same rank.
Full house - Three of a kind with a side pair.
Flush - Any five cards, all the same suit
Straight - Five cards in a sequence, any suits.
Three of a kind - Three cards all of the same rank.
Two pair - Two different pairs.
One pair - Two cards of the same rank.
High card - Highest card in your hand.
Click below to see the answer.
Hand #1 is the highest-ranking hand shown, but since all of these hands cannot occur on the same deal, it isn't the best hand to have in a real game.
To determine which hand is best, you have to look at how many other hands can beat each hand when dealt from the same deck. All of the hands above can be beaten by the same number of four-of-a-kinds, but by different numbers of straight flushes. Having two sixes as your side pair breaks up more of these possible straight flushes than having two kings, so hand #4 is actually the best hand to have. (There are 32 possible straight flushes that beat the kings hand, but only 24 that beat the sixes.)
The bridge will collapse in 17 minutes! Four people need to cross the bridge before it collapses. It is a dark night and they have only one flashlight among them.
Only two people can cross at a time.
Alice takes one minute to cross.
Bob takes two minutes.
Carol takes five minutes
Dave takes 10 minutes to cross.
How can they all get across before the bridge collapses? Click below to see the answer.
The trick to this puzzle is to get the slowest members of the group to cross only once together, while the fastest members cross back and forth multiple times.
Alice and Bob cross first using up 2 minutes.
Alice comes back making it 3.
Carol and Dave cross together making it 13 minutes.
Then Bob crosses back, making it 15 minutes.
Finally, Alice and Bob cross together to make it a total of 17 minutes.
Raymond Smullyan, one of the grand masters of logic puzzles, sadly passed away at the age of 97 earlier this week. In his honor, I present a classic puzzle adapted from his book What Is the Name of This Book?
There is a wide variety of puzzles about an island in which certain inhabitants called "knights" always tell the truth and others called "knaves" always lie. It is assumed that every inhabitant of the island is either a knight or a knave.
In this problem, there are only two people, A and B, each of whom is either a knight or a knave. A makes the following statement: "At least one of us is a knave." What are A and B?
Click below for the solution.
The solutions to these puzzles are often found by making one or more assumptions, then reasoning out whether or not it can be true. In this case, assume A is a knave. Then the statement "At least one of us is a knave" would be false, since knaves always lie. Hence, both A and B would be knights, which is impossible because we started with the assumption that A is a knave. Therefore, A must be a knight, and the statement "At least one of us is a knave" must be true, and B is a knave.
Raymond Smullyan presented a couple more of his puzzles in a 1982 interview on the Tonight Show with Johnny Carson. When you see the white hair and long beard, it seems like even 35 years ago that Smullyan was an old man, but the twinkle in his eye and the playfulness in his voice reveal that he was always a child at heart. Watch the full interview below.
If these puzzles seem too easy, they're just a small sample of Dr. Smullyan's brilliant work. If you really want a challenge, I encourage you to check out some of his books, or The Hardest Logic Puzzle Ever, also credited to Smullyan.
Finally, I leave you with a quote.
Why should I be worried about dying?
It's not going to happen in my lifetime!
The guinea pig is not a pig. It is a rodent. (And it's not even from Guinea, a country on the west coast of Africa. Guinea pigs originated in the Andes mountains in South America.)
